Just about everyone refers to the “stuff” moving around
through the A/C system as “Freon”.But
the term Freon, is actually DuPont’s trade name for their brand of refrigerant.In other words, it’s all refrigerant, but
only DuPont’s brand is called “Freon”.Today, there are many different refrigerant manufacturers, so the
refrigerant in yours might be any brand.

Refrigerant is the circulated substance that makes the A/C
work.It’s kind of like the blood
moving through your arteries.There are
many different types of refrigerants.Most of the A/C and heat pump systems currently in use contain R22,
which is currently being phased out due to concerns about its adverse effects
on the ozone layer up in the sky.2009
is the last year that systems containing R22 can be manufactured
by federal mandate.The manufacture of new
R22 itself, is due to be gradually phased out by 2020.

So a few years ago, the first systems containing R410A
refrigerant started being manufactured.All of the new systems manufactured starting in 2010 will be R410A
systems.(Update 7/23/11: AC
manufacturers have started shipping units that use but don’t contain
R22 when they leave the factory.They
contain a nitrogen holding charge instead.The installer removes the nitrogen holding charge, evacuates the system,
and charges it with R22.So it’s
apparently an end run around a loophole in the law, which states that a system containing
R22 can’t be manufactured).

The refrigerants R22 and R410A are notcompatible,
i.e. you can’t put R22 into an R410A system and vice-versa.The systems are manufactured specifically
for the refrigerant they were designed to be used with.It’s like you getting a transfusion with the
wrong blood type.

As some of you might recall, we went through the same thing
with the refrigerants used in car air conditioners and household refrigerators
back in the mid 90’s when R12 refrigerant was phased out in favor of
R134A.And now, just as then it remains
a highly controversial topic to say the least.Many of us in this industry continue to disagree about how wise these
phase-outs truly were, and what the long-term prognosis for the replacement
refrigerants is.I personally believe
that the case against some of these phased-out refrigerants has been adequately
proven, especially in the case of R12, which had a very high ozone
depletion potential.But it’s much
harder to make that same argument regarding R22, because the ODP of it is only
about 5% as high as R12.But this is a
done deal, and there’s nothing to be gained by arguing the point.

There are major differences between R22 and R410A.One such difference is that R410A is under a
much higher pressure than R22.But as
far as the cooling capacities, they are quite similar, with the R410A actually
delivering slightly more cooling than R22.

As for the future prognosis for R410A - nothing’s around
forever.Plans are already being made
to phase it out according to one of the primary refrigerant industry
manufacturers.In 2008 they stated that
while R410A has a very low ODP, it has been found to have a higher than desired
global warming potential (GWP).So far, no refrigerants have been selected to replace it.

Refrigerant FAQ

Does my A/C contain it?

Yes, unless it’s one of those very rare natural gas units.

Do I need to have more added every year?

Not unless there are leaks in the system.It goes nowhere in a sealed system.

How much does it hold?

That varies significantly depending on the size of the
outdoor unit, the indoor cooling coils and the diameter and length of the refrigerant
lines running from the outdoor unit to the indoor coils.

If I do have a leak, how long does it take for it to leak
out?

There are too many variables involved to be able to predict
it.It would be determined by how many
pounds the system holds, how many leaks and what size they are and where each
one is in the system.The system
contains high pressure sections and low pressure sections.The higher the pressures are, the more
refrigerant volume will be lost through the same size opening.In most systems, when the A/C is not running
the pressure is the same through the entire system – the pressures
equalize.So the pressure on the high
pressure side drops and pressure on the low pressure side increases.So if the leak is in the high pressure side,
it usually comes out faster when the unit is running.And conversely, if the leak is on the low pressure side, it will
usually come out faster when the unit is not running.

How do you find the leaks?

We have several different methods of doing that.The most popular leak detection method is an
electronic refrigerant detector, i.e. sniffer.It will give an audible and visual indication when a leak is sensed by
the sensing probe.Another method is
the injectable fluorescent dye which is injected into the system and it
circulates around with the refrigerant and often comes out with the refrigerant
when there’s a leak.We then use an
ultra-violet light to illuminate the refrigerant system and the dye will glow a
bright fluorescent green color where there’s a leak.Then there are the “ultrasonic” leak detectors that work on the
principle that the leaks often make an ultra-high frequency sound when the
refrigerant escapes.The sensor is
basically a microphone, which picks up the sound and converts it to a frequency
within the human hearing range.You put
on a set of headphones and can often hear the sound of the gas escaping.The units also have visual indicators that
can be used, i.e. LED lights, etc. to show you the intensity of the sound.There are also low-tech methods/devices,
like soap bubbles.And there is also a
device called a halide torch, which draws the sample in through a hose and
sends it through a blue flame.When
refrigerant is introduced into the flame, the flame changes from blue to green.(I have every one of these leak detection
devices).

Do the leaks always show up when you look for them?

Unfortunately not – for numerous reasons.Leaks come in all sizes and shapes.These are not typically round holes.They can be any shape.Metals expand and contract.Leaks can close up completely at a given set
of conditions and open up at another set of conditions.Obviously the ability to locate the leak is
much greater when more refrigerant gas per unit of time is leaking out of
them.There are situations where
nothing in the leak detection arsenal will find some of them.But I’ve had excellent success in locating
the majority of them with persistence and some really great devices.You’re only as good as your tools, and mine
are the best money can buy.I don’t
skimp in that area.(But my wardrobe is
another matter according to my wife).

Where do the leaks usually occur?

There are 3 basic parts to the system, and they can occur in
any of those parts.They can be in the outside
unit, or in the refrigerant lines going to the inside coil, or in the inside
coil itself.The least common place is
in the lines.The most common place is
typically in the indoor coil.Experience teaches us that some units have “favorite” places to leak.

Can you see the refrigerant leaks?

Almost never, unless they’re really big ones.But sometimes you can see indirect traces of
them after the fact.Refrigerant isn’t
the only thing being circulated through a system.There is also a small amount of refrigerant oil being
circulated.You can often spot
locations where there is an accumulation of oil on the surface.And that’s a very good place to focus
your leak detection efforts.Refrigerant
exists in 2 forms, i.e. states in the system – as a gas and as a liquid.You can’t see it in gas form, just as you
can’t see air.But if trace amounts of
oil are coming out with it, as in the case of a relatively large leak, you
might see the oil bubbling around the leak.The refrigerant that’s leaking out as a liquid might be visible – but it
turns to gas very quickly as it exits and reaches air.So it depends on how big the leak is, and
the shape of the leak as to whether you’d be able to see it before it turns to
a gas.

How do you fix the leaks?

There are numerous places for the leaks to occur.Some are relatively easy to repair and some
are not.Some are as simple as
tightening a connection, while others involve brazing or replacing the leaking
component.If the leak is the indoor
coil (the evaporator), the majority of the time they will occur in a location
that is not repairable.So the entire
cooling coil (evaporator) must be replaced.The same thing applies to the coils (condenser) in the outside
unit).This is the worst place the leak
can be, because the condenser replacement costs can be very close to that of
the entire outside unit.And unlike
indoor coils, where you have numerous replacement options for the replacement
cooling coil, you are limited to the exact replacement condenser coil available
from the manufacturer.And after a few
years, they no longer sell them for each model.If the leak is in the lines running through the house, the line
must obviously be accessed to repair the leak.It is almost never necessary to replace the entire line, as leaks in the
copper lines can be easily brazed shut.I’ve seen this happen when a remodeler accidentally fired a nail or
screw through a basement ceiling and punctured the refrigerant tubing.

The tubing in these lines generally has much thicker walls
that the tubing used to manufacture condenser and evaporator coils.So when you see a leak in the lines, it is
typically a “man-made” leak.

With a few exceptions, depending on where the leaks are
located, all of the refrigerant typically must be “recovered” (removed and put
in a recovery cylinder) for the leak to be repaired, because you can’t repair a
leak when the leaking part is pressurized.Exceptions to this would be if the leak is in a Shrader valve core (I
have a tool to replace it with without losing any refrigerant) or if the leak
is not in the outside unit and the outside unit has “front-seatable” valves,
which allows you to pump the refrigerant back into the outside and hold it
there while the repairs are being made.Then after the repairs are made, you hook up a vacuum pump to the system
and put the part of the system you had open (removed the refrigerant from) into
a deep vacuum to remove any air and moisture from it.Then you release the refrigerant back into the system (if you
stored it in the condenser with the front-seating valves).

Should I have a leak test if my unit is low on
refrigerant?

There are a few different scenarios with different
flow-charts involved for each one.It
really depends on the age and history of the system as to whether or not you
want to spend the money to have this done, and then go to the expense of having
it repaired once the leaks are found.One thing’s for sure.The leaks
won’t go away on their own.If you’re
lucky, they’ll merely continue to leak at the same rate if they aren’t found
and dealt with.But you have to balance
this against the cost of adding refrigerant to it, or against the cost of
replacing the system.Obviously if you
sell the property, the new owners will not want to inherit a leaking
system.Leaks come in all sizes, i.e.
all rates of leakage.So it depends on
how often it needs to have refrigerant added.The smaller the leak is, the less frequently it needs to have more
added, and the more difficult it is to find.When I go after a leak, I usually find it, although sometimes the
customer wishes I hadn’t when it’s in a really bad place.The bottom line is that it’s the customer’s
choice whether or not the leak detection will be done.I typically ask them a few questions and
based on that, throw in my 2-cents worth about what I’d do if I were in their
shoes.

If my system is low on refrigerant, does that mean I have
a leak?

It USUALLY does.But there are cases where it doesn’t.Not all technicians follow accepted procedures for checking refrigerant
levels in the system.I’ve seen quite a
few cases where the system was installed brand new without enough refrigerant
in it.Central residential A/C systems
are not plug and play devices.The
amount of refrigerant in them must be tailored to that installation.The cooler it is outside the house or inside
the house, the lower the refrigerant pressures become.There must be a minimum amount of heat
outside and/or inside the house to accurately check the refrigerant levels.If the levels are adjusted during times when
these temperatures aren’t above a certain level by experienced technicians
using the proper diagnostic methods and the proper test equipment, the unit
could very well have less than the proper amount of refrigerant in it.So that scenario would be a man-made problem
of the system merely not having enough put in it.This same scenario can occur when a part of the refrigerant system
is repaired or replaced by an inexperienced technician.

The problem is that when we visit your house for the first
time and we find the system low on refrigerant we don’t know the history of
it.So we don’t know if it was ever
filled properly to begin with.But if
it has a history of having refrigerant added to it, it’s extremely likely that
there’s an ongoing leak, unless by some rare chance a leak was repaired before
and they didn’t fill it completely afterward.

What causes refrigerant leaks?

Some of the causes for refrigerant leaks are “formicary
corrosion”, acids in the refrigerant system, poorly manufactured components,
thinner walled refrigerant carrying tubing, higher than normal refrigerant
pressures, defective solder/brazing joints, improperly made repairs, punctures,
excessive vibration/rubbing/chafing, long term immersion in fluids, and last
but not least age.The evaporator
(indoor cooling coil) usually has the hardest life, because it has water
cascading down over it constantly when the system is running.It also typically resides directly above the
heat exchangers in the furnace in most of the Greater Kansas City area
installations.So it sees some
amazingly fast changes in temperature, especially during the heating
season.

Would I know if the system is low on refrigerant?

Yes, no and “maybe”.It depends on the system, the indoor and outdoor temperatures, how
“tight” the house is, and how adequately sized the system is for that
house.You’d obviously know there was a
problem if it became extremely low on refrigerant or lost all of it, because it
would no longer cool the house at all.Basically, the lower the refrigerant amount becomes, the less cooling
per hour the system delivers compared to the amount of cooling per hour
it would deliver under those same conditions (with all of the
above-mentioned factors being the same) if the system was full of
refrigerant.The cooling power (Btu per
hour of delivered cooling) is not a constant in an A/C system.It varies with indoor and outdoor
temperatures and humidity levels.And
so does the amount of heat entering the house, which it must remove.And if the A/C system is oversized for the
house, it might still be able to remove enough heat to maintain the temperature
you have the thermostat set to.But the
unit will have to run longer to do that.How much longer depends on all those other factors.

FUNNY REFRIGERANT LEAK SCENARIOS I’VE RUN INTO

As mentioned before, refrigerant leaks will sometimes ooze
and even spray oil out of the source of the leak, leaving visual evidence (in
the form of an oily residue) of their existence.I leak tested a system once and found an abundance of oil
residueinside the outdoor unit.So I’m going over every square inch of the
outside unit with a fervor trying to locate the leak.The customer returns home, and tells me, “Oh, I set a quart of
oil on top of the unit and accidentally knocked it over.”

I leak tested an evaporator using my ultra-sonic leak
detector.Immediately after turning
leak detector on, I hear an incredibly loud noise coming from the
headphones.I’m thinking that this must
be the “mother of all leaks” to produce such a high intensity sound.But the farther away from the coil I get,
the louder the signal becomes.The customer had plugged in one of those ultra-sonic bug repeller boxes
into a nearby socket next to the light bulb.I don’t know if they actually keep the bugs away, but they definitely
create a powerful high frequency sound.I’d put them all over my house, but it would be my luck that the bugs
might be deaf.And it would be a lot of
work and quite expensive to capture and outfit them all with little miniature
ultra-sonic leak detector hearing aids.(As an interesting asides, some of these ultra-sonic leak detectors will
pick up the sound of a bat nearby, because they make a sound in that frequency
range for navigation purposes.They
actually transmit that sound and it bounces off things and returns to them and
this tells them the relative distance and size of things around them).